Neurostimulation leads for trial nerve stimulation and methods of use

ABSTRACT

Devices and methods for providing neurostimulation to a patient, particularly in trial systems assessing suitability of a permanently implanted neurostimulation. Such trial systems can utilize a trial neurostimulation lead that includes a coiled conductor coupled to a proximal contact connector that is coupled with an external pulse generator. The trial neurostimulation lead can be a coiled conductor of a closed wound configuration that can be stretched to form an open coil portion or gaps between adjacent coils to provide more resistance to migration or regression of the lead.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-provisional applicationSer. No. 17/396,260, filed Aug. 6, 2021, which is a divisional of U.S.Non-provisional application Ser. No. 16/281,857, filed Feb. 21, 2019(now U.S. Pat. No. 11,110,283), which claims the benefit of U.S.Provisional Application No. 62/633,806, filed on Feb. 22, 2018,” theentireties of which are incorporated by reference herein.

The present application is related to U.S. Non-Provisional applicationSer. No. 15/431,475, entitled “Neurostimulation Lead for Trial NerveStimulation and Methods of Use,” filed Feb. 13, 2017 and U.S.Non-Provisional application Ser. No. 14/827,081, entitled External PulseGenerator Device and Associated Methods for Trial Nerve Stimulation”filed on Aug. 14, 2015, the entire contents of which are incorporatedherein by reference in its entirety for all purposes.

BACKGROUND OF THE INVENTION

Treatments with implanted neurostimulation systems have becomeincreasingly more common in recent years. While such systems have shownpromise in treating a number of chronic conditions, effectiveness oftreatment may vary considerably between patients and viability oftreatment can be difficult to determine before implantation. Althoughconventional methods of implantation often utilize preliminary testingwith a temporary, partially implanted neurostimulation systems to assessviability of treatment, such systems may not provide an accuraterepresentation of treatment with a fully implanted device. Many suchtemporary partially implanted systems may not operate in the same manneras their fully implanted counterparts due to differences between pulsegenerators or changes in position of the neurostimulation leads due toregression or migration of the lead. Regression of a temporary lead ortined lead can also cause failure of an electrical connection of thelead or infection of a secondary incision site. Therefore, it isdesirable to provide methods and devices for providing neurostimulationleads that provide consistent treatment outcomes by improved leads andlead connections, improved implantation and removal, and more seamlessconversion from a trial system to a long-term fully implantedneurostimulation system.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to neurostimulation treatment systems, andin particular a neurostimulation leads for nerve stimulation trials orevaluations as well as and permanently implanted systems.

In one aspect, the invention pertains to a neurostimulation lead thatincludes a retention feature between a conductor and a proximal contactconnector. In some embodiments, the lead includes at least one coiledconductor extending from a proximal portion of the neurostimulation leadto a distal electrode on a distal portion of the neurostimulation leadand a proximal contact connector electrically coupled with the at leastone coiled conductor and configured for electrically connecting the leadto a pulse generator or to an external cable which then connects to thepulse generator. The proximal contact connector includes a distalretention flange and a reduced profile coupling portion proximal of thedistal retention flange, wherein one or more coils of the conductor arepositioned along the coupling portion and fixedly attached thereto. Oneor more coils engage the proximal facing surface of the retention flangeso as to resist tension between the coiled lead and proximal contactconnector and maintain integrity of electrical connection between thecoiled conductor and the coupling portion of the proximal contactconnector.

In some embodiments, the retention flange includes a distal facing rampsurface extending at least partly about the circumference of theproximal contact connector to facilitate assembly of the coiledconductor with the proximal contact connector. In some embodiments, theretention flange includes an open notch portion having a reduced radiusas compared to a remainder of the flange so as to allow the coiledconductor to be screwed onto the coupling portion past the flange. Insome embodiments, the open notch portion is between 90 to 160 degreesabout the circumference. The ramped surface of the retention flange isramped, for example at an angle between 30 and 60 degrees, typicallyabout 45 degrees to facilitate feeding of the coiled lead upon theconnector. The proximal facing retention surface of the retention flangeextends substantially perpendicular to a longitudinal axis of theproximal connector.

In some embodiments, the coiled conductor is fixedly attached andelectrically coupled to the coupling portion of the proximal contactconnector by soldering or laser welding. The proximal contact connectorcan include a proximal portion that is elongate to facilitate connectionof the lead to a pulse generator and includes a proximal opening tofacilitate introduction of a stylet through an open lumen of the lead.

In some embodiments, the retention flange is configured to withstand atensile force of at least 5 N. In the application described herein, theretention flange is configured to withstand a minimum tensile force of10-12 N. It is appreciated that the desired minimum tensile force canvary according to the properties of a particular lead or application.

In some embodiments, the lead further includes an outer insulatorcoating disposed on the coiled conductor along at least an intermediateportion of the neurostimulation lead between the proximal portion andthe distal electrode, wherein the distal electrode is defined by anexposed portion of the coiled conductor without the outer insulatorcoating. In some embodiments, the neurostimulation lead hassubstantially the same outer diameter along the coiled conductor and theproximal contact connector to facilitate passage of the lead through aforamen needle. In some embodiments, a majority of the coiled conductoris closed wound at a first pitch. The coiled conductor includes one ormore open coiled portions wound at a second pitch, wherein the one ormore open coiled portions are positioned at distances from the distalelectrode that correspond to a length of one or more foramen needles.

In some embodiments, the neurostimulation lead includes a singleelectrode has a surface area within a range of about 0.01 in² to 0.1in². The length or surface area of the first electrode can be configuredto correspond to a dimension of an electrode portion of an implantableneurostimulation lead to be placed after percutaneous nerve evaluation.Such neurostimulation leads can be utilized for sacral nervestimulation, in particular the lead is suited for use as a trialstimulation lead for percutaneous nerve evaluation.

In some embodiments, the neurostimulation lead includes one or moreadditional conductors extending from the proximal portion of theneurostimulation lead to one or more additional electrodes along thedistal portion of the neurostimulation lead. The one or more additionalcoiled conductors can be electrically coupled and fixedly attached tothe coupling portion of the proximal contact connector and one or morecoils of each of the one or more additional coiled conductors aredisposed proximal of the retention flange. In some embodiments, thecoiled conductor and the one or more additional conductors are definedby a multi-ribbon conductor. In other embodiments, a multi-electrodelead can include multiple insulated conductors wound about a tube havinga central lumen.

In any of the neurostimulation leads described herein, the conductor orlead body can include a coating of the coiled conductor comprised of atextured surface configured to provide improved retention along at leastthe one or more retention features. In some embodiments, the coatingincludes a barbed surface having a plurality of barbs oriented toinhibit movement of the neurostimulation lead.

In some embodiments, a neurostimulation lead defined by one or morecoiled conductors includes an open coil pitch along at least a portionof an implantable length of the lead so as to resist migration of thelead. The open coil pitch can be of the same diameter as the closedcoiled portions. Such open coiled portions can be formed during windingof the lead, as opposed to being formed by stretching or elongatingclosed wound portions, so as to avoid plastic deformation of theconductor.

In another aspect, a neurostimulation lead can include one or moreanchors attached thereto. In some embodiments, such leads can include aretractable anchoring feature at a distal end, the anchoring featureattached to an elongate member extending through the proximal contactconnector such that retraction of the elongate member retracts thedistal anchor into a central lumen of the coiled conductor. In otherembodiments, a lead can include a bioabsorbable anchor disposed at adistal end or adjacent the distal electrode, the anchor being configuredto absorb after expiration of the trial period to allow ready removal ofthe lead. In some embodiments, the bioabsorbable anchor includes aradiopaque marker that remains within the body after the anchor absorbsto allow positioning of an electrode of a permanently implanted lead atthe same location as the distal electrode of the lead. It is appreciatedthat these anchoring features are applicable to any type of lead (e.g.,coiled, non-coiled, single electrode, multi-electrode) and for anyapplication.

In another aspect, a neurostimulation lead having one or more coiledconductors can include a helical tined anchor configured to attach tothe coiled conductor. In some embodiments, the helical tined anchor iswound at a same pitch as a portion of the conductor to which the anchoris attached. The helical tined anchor is formed of any suitable material(e.g. metal, polymer). In some embodiments, the anchor is formed ofNitinol and formed by heat setting so that the tines extend outward fromthe lead body when attached. In some embodiments, the helical tinedanchor is configured to attach to an outer surface of a closed woundportion of the lead along or adjacent the distal electrode. In otherembodiments, the helical tined anchor configured to attach to aninterior portion of an open coil pitch portion of the coiled conductorsuch that the tines extend outward from the lead. In some embodiment,the helical tined anchor is configured to attach to a distal end of thelead and includes a distal atraumatic tip to provide an end stop for astylet inserted within the coiled conductor.

In another aspect, methods of assembling a neurostimulation lead areprovided herein. Such methods include assembly of trial leads,particularly PNE leads. Such methods can include: feeding at least onecoiled conductor over a distal retention flange of a proximal contactconnector so as to position one or more coils of the coiled conductoralong a reduced profile coupling portion of the proximal contactconnector proximal of the distal retention flange and electricallycoupling and fixedly attaching the coiled conductor to the couplingportion by soldering or welding. Such methods further include engaging aproximal facing surface of the distal retention flange with a portion ofthe one or more coils disposed proximal of the retention flange so as towithstand tensile forces applied by tension in the lead, therebymaintaining the integrity of the electrical connection between thecoiled conductor and the proximal contact connector. In someembodiments, a cover or shrink tube is advanced over the interface ofthe coiled conductor and the proximal contact connector for protection.

In some embodiments, the methods of assembling neurostimulation leadscan include attaching one or more anchoring features, the one or moreanchoring features including any of a helical anchor disposed along anouter surface of a closed wound portion of the lead, a helical anchordisposed within an open coil pitch portion of the lead, a retractableanchor that retracts into a central lumen of the lead, a bioabsorbableanchor that absorbs after a duration of a trial period, a bioabsorbablelead having a radiopaque marker that remains within the body after theanchor is dissolved.

In another aspect, a lead extension is provided herein. Such a leadextension can include a distal connector and proximal connector coupledvia an extension cable. The distal connector is configured forelectrically coupling with a fully implanted lead. The proximalconnector is configured for coupling with an external pulse generator orintervening connection. The proximal connector is dimensioned forpassage through a tool or cannula tunneled from a first incision area ofa body of a patient and through a second incision outside the patient'sbody; an extension cable electrically coupling the distal connector withthe proximal connector; and a regression stopper disposed on theextension cable between the proximal connector and the distal connectorand configured to prevent regression of the proximal connector into apatient's body through the second incision, wherein the regressionstopper is dimensioned for passage through the tunneled tool or cannulaalong with the proximal connector. In some embodiments, the regressionstopper has a distal facing surface that is substantially perpendicularto a longitudinal axis of the extension cable so as to interface with askin of the patient or associated pad or gauze thereon so as to inhibitregression of the lead through the second incision. In some embodiments,the regression stopper is substantially cylindrical in shape, althoughit is appreciated various other shapes can be used. In some embodiments,the regression stop can be adjustable or removable, or configured toattach to a larger regression stopper feature.

In another aspect, methods of utilizing such a lead extension areprovided. Such methods can include: implanting a neurostimulation leadin a body of a patient such that a proximal end of the lead is disposedat a first incision area; tunneling from the first incision area to asecond incision; connecting a distal connector of the lead extension atthe first incision area and implanting the distal connector at the firstincision area, the distal connector being electrically coupled with aproximal connector of the lead extension via an extension cableincluding a regression stopper; and passing a proximal connector and theregression stopper through a tool or cannula tunneled from the firstincision and through the second incision outside the patient's body. Thetool or cannula are then removed. Engaging, with the regression stopper,an outer skin of the patient or a pad or gauze disposed thereon inhibitregression of the lead into the patient during a trial period or duringexplant of the lead extension. This prevents infection of the secondincision site and facilitates removal of the lead extension after thetrial.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating various embodiments, are intended for purposes ofillustration only and are not intended to necessarily limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a trial neurostimulation systemhaving a partially implanted lead extending to an EPG patch adhered tothe skin of the patient, in accordance with some embodiments of theinvention.

FIG. 2A shows an example neurostimulation system for a percutaneousnerve evaluation with a single electrode coiled lead.

FIG. 2B shows an example neurostimulation system for a trial period witha fully implanted tined lead and lead extension.

FIG. 3 is an example configuration of a trial neurostimulation system,in accordance with some embodiments.

FIG. 4 is yet another alternative configuration of a trialneurostimulation system, in accordance with some embodiments.

FIG. 5 illustrates an EPG and an associated schematic in accordance withsome embodiments.

FIG. 6 shows a schematic of an EPG in accordance with some embodiments.

FIGS. 7A-7B illustrate an alternative EPG in accordance with someembodiments.

FIGS. 8A-8B illustrate a neurostimulation lead configured for apercutaneous nerve evaluation or trial period, in accordance with someembodiments.

FIGS. 9A-9C illustrate perspective, front and side views, respectively,of a proximal contact connector of the neurostimulation lead of FIG. 8A.

FIGS. 10A-10B illustrate front and side views, respectively, of a distalportion of the proximal contact connector, in accordance with someembodiments.

FIG. 11-13B illustrate several views of an extension cable having aregression stopper, in accordance with some embodiments.

FIGS. 14A-14B illustrate an example EPG and lead extension and tine leadin accordance with some embodiments.

FIG. 15 schematically illustrates a use of a trial neurostimulationsystem utilizing an EPG affixation device in accordance with someembodiments.

FIG. 16 illustrate a method of assembling a neurostimulation lead havinga coiled conductor, in accordance with some embodiments.

FIG. 17 illustrate a method of use of a neurostimulation lead extensioncable for a neurostimulation trial period in accordance with someembodiments.

FIG. 18 illustrates an anchoring feature for use in a neurostimulationlead in accordance with some embodiments.

FIGS. 19A-19C illustrate a closed coil and open coil design ofmulti-electrode neurostimulation leads defined by a multi-conductorribbon, such as that shown in the cross-section of FIG. 19C, inaccordance with some embodiments.

FIGS. 20A-20B illustrate cross-sections of multi-conductor designshaving multiple conductors arranged about a central core or conduit foruse in multi-electrode neurostimulation leads in accordance with someembodiments.

FIGS. 21A-21B illustrate a coiled neurostimulation lead having aretractable anchor feature, before and after retraction respectively, inaccordance with some embodiments.

FIG. 22 illustrates a coiled neurostimulation lead having abioabsorbable anchor feature in accordance with some embodiments.

FIGS. 23A, 23B and 23C illustrate coiled neurostimulation leads havinganchoring features that interface within coiled portions of the lead inaccordance with some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Neurostimulation has been used for many years to treat a variety ofconditions, from chronic pain, to erectile dysfunction and variousurinary dysfunctions. While neurostimulation has proven effective inmany applications, effective therapy often relies on consistentlydelivering therapeutic activation by one or more neurostimulationelectrodes to particular nerves or targeted regions with a pulsegenerator. In recent years, fully implantable neurostimulation havebecome increasingly more commonplace. Although such implantable systemsprovide patients with greater freedom and mobility, the neurostimulationelectrodes of such systems are more difficult to adjust once they areimplanted. The neurostimulation electrodes are typically provided on adistal end of an implantable lead that is advanced through a tunnelformed in a patient tissue.

FIG. 1 schematically illustrates a use of a trial neurostimulationsystem utilizing an EPG affixation device, in accordance with aspect ofthe invention. Such a trial neurostimulation system can be used toassess viability of a fully implantable neurostimulation system.Implantable neurostimulation systems can be used in treating patientswith, for example, chronic, severe, refractory neuropathic painoriginating from peripheral nerves or various urinary and boweldysfunctions. Implantable neurostimulation systems can be used to eitherstimulate a target peripheral nerve or the posterior epidural space ofthe spine. An implantable neurostimulation system includes an implantedpulse generator, typically implanted in a lower back region. In someembodiments, the pulse generator can generate one or more non-ablativeelectrical pulses that are delivered to a nerve to control pain or causesome other desired effect. In some applications, the pulses having apulse amplitude of between 0-1,000 mA, 0-100 mA, 0-50 mA, 0-25 mA,and/or any other or intermediate range of amplitudes may be used. One ormore of the pulse generators can include a processor and/or memoryadapted to provide instructions to and receive information from theother components of the implantable neurostimulation system. Theprocessor can include a microprocessor, such as a microprocessor fromIntel® or Advanced Micro Devices, Inc.®, or the like. An implantablepulse generator may implement an energy storage feature, such as one ormore capacitors or a battery, and typically includes a wireless chargingunit.

The electrical pulses generated by the pulse generator are delivered toone or more nerves and/or to a target location via one or more leadsthat include one or more neurostimulation electrodes at or near thedistal end. The leads can have a variety of shapes, can be a variety ofsizes, and can be made from a variety of materials, which size, shape,and materials can be dictated by the application or other factors. Insome applications, the leads may be implanted to extend along the spineor through one of the foramen of the sacrum, such as shown in FIG. 1,such as in sacral nerve stimulation. In other applications, the leadsmay be implanted in a peripheral portion of the patient's body, such asin the arms or legs, and can be configured to deliver one or moreelectrical pulses to the peripheral nerve such as may be used to relievechronic pain.

One or more properties of the electrical pulses can be controlled via acontroller of the implanted pulse generator. In some embodiments, theseproperties can include, for example, the frequency, strength, pattern,duration, or other aspects of the timing and magnitude of the electricalpulses. These properties can include, for example, a voltage, a current,or the like. This control of the electrical pulses can include thecreation of one or more electrical pulse programs, plans, or patterns,and in some embodiments, this can include the selection of one or morepre-existing electrical pulse programs, plans, or patterns. In theembodiment depicted in FIG. 1, the implantable neurostimulation system100 includes a controller in the implantable pulse generator having oneor more pulse programs, plans, or patterns and/or to select one or moreof the created pulse programs, plans, or patterns.

Sacral neuromodulation (SNM), also known as sacral nerve stimulation(SNS), is defined as the delivery of mild electrical pulses to thesacral nerve to modulate the neural pathways controlling bladder andrectal function. This policy addresses use of SNM in the treatment ofurinary or fecal incontinence, urinary or fecal nonobstructiveretention, or chronic pelvic pain in patients with intact neuralinnervation of the bladder and/or rectum.

Treatment using SNM, also known as SNS, is one of several alternativemodalities for patients with fecal incontinence or overactive bladder(urge incontinence, significant symptoms of urgency-frequency) ornonobstructive urinary retention who have failed behavioral (e.g.,prompted voiding) and/or pharmacologic therapies. Urge incontinence isdefined as leakage of urine when there is a strong urge to void.Urgency-frequency is an uncontrollable urge to urinate, resulting invery frequent small volumes. Urinary retention is the inability tocompletely empty the bladder of urine. Fecal incontinence is theinability to control bowel movements resulting in unexpected leakage offecal matter.

The SNM device consists of an implantable pulse generator that deliverscontrolled electrical impulses. This pulse generator is attached to wireleads that connect to the sacral nerves, most commonly the S3 nerveroot. Two external components of the system help control the electricalstimulation. A patient remote control may be kept by the patient and canbe used to control any of the variety of operational aspects of the EPGand its stimulation parameters. In one such embodiment, the patientremote control may be used to turn the device on or return the EPG to ahibernation state or to adjust stimulation intensity. A consoleprogrammer is kept by the physician and used to adjust the settings ofthe pulse generator.

In a conventional approach, prior to implantation of the permanentdevice, patients undergo an initial testing phase to estimate potentialresponse to treatment. The first type of testing developed waspercutaneous nerve evaluation (PNE). This procedure is done under localanesthesia, using a test needle to identify the appropriate sacralnerve(s). Once identified, a temporary wire lead is inserted through thetest needle and left in place for 4 to 7 days. This lead is connected toan external stimulator, which can be carried by patients in theirpocket, secured against the skin under surgical dressings, or worn in abelt. The results of this test phase are used to determine whetherpatients are appropriate candidates for the permanent implanted device.For example, for overactive bladder, if patients show a 50 percent orgreater reduction in symptom frequency, they are deemed eligible for thepermanent device.

The second type of testing is a 2-stage surgical procedure. In Stage 1,a quadripolar-tined lead is implanted (stage 1). The testing phase canlast as long as several weeks, and if patients show a specifiedreduction in symptom frequency, they can proceed to Stage 2 of thesurgery, which is permanent implantation of the neuromodulation device.The 2-stage surgical procedure has been used in various ways. Theseinclude its use instead of PNE, for patients who failed PNE, forpatients with an inconclusive PNE, or for patients who had a successfulPNE to further refine patient selection.

In one aspect, the duration of battery life of the EPG is at least fourweeks for a tined lead at nominal impedance (e.g. about 1200 Ohms), anamplitude of about 4.2 mA, and a pulse width of about 210 us, or theduration of battery life can be at least seven days for a PNE lead. Insome embodiments, the battery is rechargeable and can be recharged bycoupling the battery with a standard 120 V wall outlet, and mayoptionally utilize the same power cables or adapter as used by othersystem components (e.g. clinician programmer). Typically, the EPG iscurrent controlled. The EPG can be configured with a pulse width between60-450 μs, a maximum stimulation rate between 2 and 130 Hz, a maximumamplitude between 0 and 12.5 mA, a stimulation waveform that is biphasiccharge-balanced asymmetric, minimum amplitude steps of about 0.05 mA,continuous or cycling operating modes, a set number of neurostimulationprograms (e.g. two programs), ramping capability, and optional alertbuilt into the EPG.

The permanent device is implanted under local or general anesthesia. Anincision is made over the lower back and the electrical leads are placedin contact with the sacral nerve root(s). The wire leads are extendedunderneath the skin to a pocket incision where the pulse generator isinserted and connected to the wire leads. Following implantation, thephysician programs the pulse generator to the optimal settings for thatpatient.

One example of a common process for treating bladder dysfunction is toemploy a trial period of sacral neuromodulation with either apercutaneous lead or a fully implanted lead in patients that meet all ofthe following criteria: (1) a diagnosis of at least one of thefollowing: urge incontinence; urgency-frequency syndrome;non-obstructive urinary retention; (2) there is documented failure orintolerance to at least two conventional therapies (e.g., behavioraltraining such as bladder training, prompted voiding, or pelvic muscleexercise training, pharmacologic treatment for at least a sufficientduration to fully assess its efficacy, and/or surgical correctivetherapy); (3) the patient is an appropriate surgical candidate; and (4)incontinence is not related to a neurologic condition.

Permanent implantation of a sacral neuromodulation device may beconsidered medically necessary in patients who meet all of the followingcriteria: (1) all of the criteria (1) through (4) in the previousparagraph are met; and (2) trial stimulation period demonstrates atleast 50% improvement in symptoms over a period of at least one week.

Other urinary/voiding applications of sacral nerve neuromodulation areconsidered investigational, including but not limited to treatment ofstress incontinence or urge incontinence due to a neurologic condition,e.g., detrusor hyperreflexia, multiple sclerosis, spinal cord injury, orother types of chronic voiding dysfunction. (See policy description ofsacral nerve neuromodulation/stimulation coverage provided by Blue CrossBlue Shield available online at:http://www.bcbsms.com/com/bcbsms/apps/PolicySearch/views/ViewPolicy.php?&noprint=yes&path=%2Fpolicy %2Femed%2FSacral_Nerve_Stimulation.html)

In another conventional approach, a similar method is used in peripheralneurostimulation (PNS) treatment systems. Generally, candidates forperipheral neurostimulation are assessed to determine their suitabilityfor undergoing the PNS procedure. Prior to the surgery, the patient willundergo pre-surgical testing that includes routine blood tests as wellas neuropsychological evaluation. The PNS procedure itself is typicallyperformed in two separate stages. Each stage takes about one hour, andthe patient can go home the same day.

In this aspect, Stage 1 involves implanting of trial electrodes, viasmall needles, which are connected to an external pulse generator (EPG),typically worn on a belt of the patient. A number of stimulationprograms are administered over the next few days. If this trialdemonstrates a significant improvement in the patient's headache orfacial pain, permanent implantation can take place. In Stage 2, a newset of electrodes, the width of angel-hair pasta, are implanted underthe skin. These are connected to a smaller implantable pulse generatorimplanted under the skin in the chest, abdomen, or back.

Among the drawbacks associated with these conventional approaches, isthe discomfort associated with wearing an EPG. The effectiveness of atrial period such as in PNE and Stage 1 trial periods are not alwaysindicative of effective treatment with a permanent implanted system. Inone aspect, since effectiveness of treatment in a trial period may rely,in part, on a patient's subjective experience, it is desirable if thediscomfort and inconvenience of wearing an EPG by the patient can beminimized so that the patient can resume ordinary daily activitieswithout constant awareness of the presence of the EPG and treatmentsystem. This aspect can be of particular importance in treatment ofoveractive bladder and erectile dysfunction, where a patient's awarenessof the device could interfere with the patient's experience of symptomsassociated with these conditions.

In one aspect, the invention allows for improved assessment of efficacyduring trial periods by providing a trial system having improved patientcomfort so that patients can more easily recognize the benefits andeffectiveness of treatment. In another aspect, the portions of the EPGdelivering the therapy are substantially the same as the IPG in thepermanent system such that the effects in permanent treatment should bemore consistent with those seen in the trial system.

In certain embodiments, the invention provides an EPG patch worn on askin of the patient so as to improve patient comfort. Optionally, theEPG used in Stage 1 may be smaller than the IPG used in thecorresponding Stage 2 so that the EPG can easily be supported by andsealed against contamination by an adherent patch that covers the EPG.In one aspect, the EPG is a modified version of the implantable IPG usedin Stage 2. The IPG may be modified by removal of one or morecomponents, such as removal of a remote charging coil with a smallerbattery and associated components. In addition, the EPG may use athinner, lighter housing than the IPG, since the EPG is not required tolast for many years, such as the IPG would be. The EPG therefore, may beconfigured to be disposable. These aspects allow the EPG to be supportedwithin a patch adhered to the skin of the patient at a convenient andcomfortable location.

FIG. 1 illustrates an example trial neurostimulation system 100 havingan EPG patch 10. As shown, the neurostimulation system is adapted tostimulate a sacral nerve root. The neurostimulation system 100 includesan EPG 40 attached to the lower back region, from which aneurostimulation lead 60 extends through a foramen of the sacrum toelectrodes (not shown) disposed near the sacral root. Theneurostimulation lead 60 further includes an anchor (not shown) disposedon a dorsal side of the sacrum. It is appreciated, however, that theanchor may be disposed on a ventral side of the sacrum as well, orwithin the foramen itself. In one aspect, the EPG 40 is disposable anddiscarded after the trial is complete. Typically, the trial may lastanywhere from 4 days to 8 weeks. Typically, an initial assessment may beobtained after 4-7 days and, if needed, effectiveness of treatment maybe examined after a few weeks, typically about 2 weeks. In one aspect,the EPG 40 of the EPG patch 10 is of a substantially similar design asthe IPG that would be implanted if the trial proves successful, however,one or more components may be removed to allow the EPG to be smaller insize, lower in mass, and/or differing materials are used since thedevice may be intended for one time use. It is appreciated that the EPG40 could be supported during the trial by various other approaches, suchby use of surgical tape, a belt or holster.

FIG. 2A shows an embodiment of neurostimulation system 100, similar tothat in FIG. 1, in more detail. As can be seen, the neurostimulationlead 60 includes a neurostimulation electrode 62 at a distal endconfigured for PNE use and is electrically connected to EPG 40 by aproximal contact connector 66, typically through trial cable. The EPG 40is supported within an adherent patch 11 when attached to a skin of thepatient. Optionally, another adherent patch 16 and surgical tape 17 canbe used to cover the incision where the lead or cable exits thepatient's body. The features of the proximal contact connector 66 aredescribed in further detail in FIGS. 8A-10B.

FIG. 2B illustrates an alternate embodiment of neurostimulation system100, similar to that in FIG. 1, in more detail. System 100 includes atined neurostimulation lead 20 attached to EPG 40 via lead extensioncable 22 at connector 21. Lead extension cable 22 includes a regressionstopper 74. As can be seen, the neurostimulation lead 20 includes aplurality of neurostimulation electrodes 30 at a distal end of the leadand an anchor 50 having a plurality of tines disposed just proximal ofthe electrodes 30. Regression stopper 74 inhibits movement of the leadinto the patient's body at the secondary incision site. The tinedanchors are disposed near and proximal of the plurality of electrodes soas to provide anchoring of the lead relatively close to the electrodes.The EPG 40 is supported within an adherent patch 11 when attached to askin of the patient. Optionally, another adherent patch 16 and surgicaltape 17 can be used to cover the incision where the lead or cable exitsthe patient's body. Examples of regression stoppers and lead extensionsare detailed further in FIGS. 3B, 3C and 11-13B.

FIG. 3 illustrates an alternate configuration in which the lead issufficiently long to allow the EPG patch 10 to be placed to allow thepatient more mobility and freedom to resume daily activities that doesnot interfere with sitting or sleeping. Excess lead can be secured by anadditional adherent patch 16 and surgical tape 17, as shown by thecenter patch in FIG. 3A. In one aspect, the lead is hardwired to theEPG, while in another the lead is removable connected to the EPG througha port or aperture in the top surface of the flexible patch 11. In oneaspect, the EPG patch and extension cable are disposable such that theimplanted lead can be disconnected and used in a permanently implantedsystem without removing the distal end of the lead from the targetlocation. In another aspect, the entire trial system can be disposableand replaced with a permanent lead and IPG. In one aspect, the EPG unitmay be wirelessly controlled by a patient remote in a similar oridentical manner as the IPG of a permanently implanted system would be.The physician may alter treatment provided by the EPG through use of aportable clinician unit and the treatments delivered are recorded on amemory of the device for use in determining a treatment suitable for usein a permanently implanted system. Such systems can include a trial PNElead such as that shown in FIGS. 8A-8B.

FIG. 4 illustrates an alternate configuration in which a tinedneurostimulation lead 20 is connected through a connector 21 at a firstincision site, via a lead extension that is tunneled to a secondaryincision site where it exits the body. This allows for the implantedlead to be used for both the trial and permanent system. This alsoallows the lead 20 of a length suitable for implantation in a permanentsystem to be used. Three access locations are shown: two percutaneouspuncture sites, one for the lead implantation over the sacral area, andone for the extension exit site, while in between the puncture locationsan incision (>1 cm) is made for the site of the connection of the lead20 and the extension cable 22. Lead extension 22 includes regressionstopper 74 that is positioned outside the body so as to engage an outerskin of the patient and inhibit subsequent regression of the lead intothe patient's body during the trial or during explant. This approachminimized movement of the implanted lead 20 during conversion of thetrial system to a permanently implanted system. During conversion, thelead extension 22 can be removed along with the connector 21 and theimplanted lead 20 attached to an IPG that is placed permanentlyimplanted in a location at or near the site of the first percutaneousincision. In one aspect, the connector 21 may include a connectorsimilar in design to the connector on the IPG. This allows the proximalend of the lead 20 to be coupled to the lead extension 22 through theconnector 21 and easily detached and coupled to the IPG duringconversion to a permanently implanted system.

FIG. 5 illustrates an example EPG 40 for use in a neurostimulation trialin accordance with various aspects of the invention. EPG 40 includes asubstantially rigid outer shell or housing 41, in which is encased astimulation pulse generator, a battery and associated circuitry. EPG 40also includes a connector receptacle 42 accessed through an opening orport in the outer housing 41 and adapted to electrically connect with aproximal lead connector 24 of a neurostimulation lead 20′. Although EPG40 is shown connected with neurostimulation lead 20′, lead 20, cables 22may also be connected to EPG 40. Connector receptacle 42 includesmultiple electrical contacts (e.g. six contact pins, eight-contactspins), all or some of which can be connected to corresponding contactspoints on a connector coupled thereto, depending on the type ofconnector. Connector receptacle 42 could be configured according tovarying types of connector standards beyond that shown, for example, aUSB or lightning cable connector. Lead connector 24 can include aproximal plug or boot 25 that sealingly engages the port when leadconnector 24 is matingly connected within connector receptacle 42 tofurther secure the mated connectors and seal the port from intrusion ofwater, humidity or debris. Boot 25 can be formed of a pliable material,such as an elastomeric polymer material, that is fittingly receivedwithin the port so as to provide ingress protection. In someembodiments, this configuration provides an ingress protection rating(IPR) is provided at IP24 or better. In this embodiment, connectorreceptacle 42 includes multiple electrical contacts, each operativelycoupled with the stimulation pulse generator, so that the EPG candeliver neurostimulation pulses to multiple neurostimulation electrodesof the lead when coupled to the connector receptacle 42.

In one aspect, EPG 40 is configured with a multi-purpose connectorreceptacle 24. For example, connector receptacle 42 can be coupled witheither a neurostimulation lead 20′ as described above, or can be coupledwith a power connector of a charging cord to allow recharging of aninternal battery of EPG 40. Such a configuration is advantageous as itallows the EPG housing 41 to be designed with a single opening or accessport, which further reduces the potential exposure of internalcomponents to water and debris, since the port is sealingly occupied bythe lead connector during delivery of therapy during the trial period.In contrast, a device having a separate charging port would likelyeither remain open or may require use of a removable plug or cover toseal the additional port.

In another aspect, EPG 40 is designed as a substantially planarpolygonal prism having parallel major surfaces that are positioned flatagainst the patient's body when affixed to the patient during the trialperiod, such as the rectangular prism shown in FIG. 5.

FIG. 6 shows a schematic of the example EPG 40 having a multi-purposeconnector receptacle 42. EPG 40 includes the stimulation pulse generator46 and rechargeable battery 48 each coupled to connector receptacle 42via associated circuitry 47 that controls delivery of power to and fromthe rechargeable battery 48 and the stimulation pulse generator 46 andconnector receptacle 42. Circuitry 47 can include one or moreprocessors, controllers and a recordable memory having programmableinstructions recorded thereon to effect control of the stimulation pulsegeneration, rechargeable battery discharge and charging, and indicator44. In some embodiments, memory includes pre-programmable instructionsconfigured to effect multiple different operating modes, for example thetherapy mode and charging mode. In the therapy mode, circuitry 47 usesthe rechargeable battery 48 to power the stimulation pulse generator 46,which produces stimulation pulses that are delivered to a connectedneurostimulation lead via the connector receptacle 42. In the chargingmode, circuitry 47 controls delivery of power delivered via theconnector receptacle 42 to rechargeable battery 48. In some embodiments,circuitry 47 includes a controller that switches between differingmodes, which can be effected upon connection of a certain connectortypes into connector receptacle 42. For example, in some embodiments,EPG 40 can include a detector that can detects a certain type ofconnector (e.g. lead connector, charging connector). In otherembodiments, a connector type can be determined by measurement ordetection of electrical characteristics of the connection. For example,a charging connection may require electrically connectivity with only acertain number of electrical contacts (e.g. one, two, etc.) and aground, while a neurostimulation lead may connect with all of thedesignated electrical contacts without any grounding required. In someembodiments, the mode can be set be manually or wirelessly set by a useras needed.

In another aspect, trial neurostimulation system 100 includes anaffixation device that secures EPG 40 to the patient while connected toa neurostimulation lead implanted at a target tissue within the patient.Typically, the affixation device is configured to secure the EPG on amid-portion (e.g. lower back region) or hip of the patient, eitherthrough an adherent patch applied directly to a skin of the patient or aclip device that can be releasably attached to a garment of the patient.Various examples of differing types of affixation devices are describedherein.

FIGS. 7A-7B illustrate an alternative EPG 50 that includes a housing 51from which a short cable connector 52 extends to a lead connector 53. Inthis embodiment, lead connector 53 is a multi-pin connector suitable forelectrically connecting to a neurostimulation lead having multipleelectrodes through an intermediate adapter or lead extension cable (seeFIG. 13). Typically, cable connector 52 is relatively short, for examplea length between 1 and 12 inches, preferably 3 and 6 inches. In thisembodiment, the multi-pin connector is a 4-pin connector suitable forconnecting to a neurostimulation lead having four electrodes, however,it is appreciated that lead connector could include differing numbers ofpins so as to be suitable for connection with neurostimulation leadshaving greater or fewer neurostimulation electrodes. In otherembodiments, the lead connector can be configured with a receptacle 42for connecting with a proximal lead connector of a neurostimulationlead, such as described previously in other embodiments. The EPG can beused with a tined lead trial or a temporary lead (PNE lead) trial.Configuring the connection to the lead external of the housing allowsthe EPG to be even smaller and lighter than those with the connectionintegrated within the device. Such a configuration also allows for somemovement for adjustment or handling of the EPG while minimizing movementof the proximal lead connector, which can be secured by tape to thepatient's body just proximal of the connector.

In some embodiments, the short cable connector 52 or “pigtail connector”is integrated with the EPG such that the electrical connections betweenthe cable and the internal electronics of the EPG are permanentlyattached and sealed. This allows the EPG to further withstand intrusionof fluids and moisture during the trial stimulation period.

Depending on the selection of cables desired for use, the EPG may beused with a PNE lead (which may have one or more than one electrode andconductor), or a permanent lead. In addition, the EPG may be used forbilateral stimulation (the use of two leads, one for each for apatient's left and right sides) when a bilateral connector cable is usedbetween the EPG and leads.

In some embodiments, the EPG includes a non-rechargeable single-usepower source (e.g. battery) having sufficient power for operation of theEPG for at least the duration of the trial period (e.g. days, weeks,months). In such embodiments, the power source can be integrated andnon-removable or non-replaceable by the patient.

As can be seen in FIG. 7B, EPG housing 51 can be defined as twointerfacing shells, top shell 51 a defining the outer major surface anda majority of the side surfaces and bottom shell 51 b defining anunderside surface. In this embodiment, EPG has a substantiallyrectangular (e.g. square) prism with rounded edges. The top majorsurface can be shaped with a slightly convex contour, while theunderside includes a substantially flattened surface for placementagainst the patient. Typically, the interfacing shells 51 a, 52 b areformed of a rigid or semi-rigid material, such as hardened polymer, soas to protect and seal the electronics within.

In some embodiments, the EPG includes one or more user interfacefeatures. Such user interface features can include any of a button,switch, light, touch screen, or an audio or haptic feature. In theembodiment shown in FIGS. 7A-7B, EPG 50 includes a button 55 and an LEDindicator 54. Button 55 is configured to turn EPG 50 on from an off orhibernation state. When turned on, EPG can communicate with an externaldevice, such as a clinician programmer to receive programminginstructions, and can deliver stimulation to a connectedneurostimulation lead while in an operating state. While button 55 canbe used by the patient to turn EPG 50 on, it is appreciated that thisfunctionality can be concurrent with any other functionality describedherein. For example, EPG 50 can be further configured to be turned onfrom an off or hibernation state by use of a patient remote or can beconfigured to suspend delivery of stimulation upon detachment of theneurostimulation lead. It is appreciated that while a button isdescribed in this embodiment, any actuatable user interface featurecould be used (e.g. switch, toggle, touch sensor) that is typicallyactuatable between at least two states.

In this embodiment, EPG 50 is configured such that pressing button 55turns on a communication function of the EPG. Once actuated, the EPG hasa pre-determined period of time (e.g. 60 seconds, 90 seconds) towirelessly connect to an external programmer (e.g. ClinicianProgrammer). If the EPG connects to the clinician programmer, the EPGstays on to facilitate programming and operating to deliver ofstimulation per programming instructions. If connection is notsuccessful, the EPG automatically turns of. If button 55 is pressed whenEPG is on, nothing happens and the communication or operating remainsunchanged. If a patient desires to turn off stimulation, the patientremote could be used or alternatively, detachment of theneurostimulation lead could also suspend stimulation. Since subsequentpressing of button 55 during operation does not turn the EPG to the offor hibernation state, the button can be positioned on an underside ofthe EPG that is placed against the patient when worn during the trialstimulation period, although it is appreciated that the button could bedisposed anywhere on the housing of the EPG. Thus, in this embodiment,the functionality of button 55 facilitates initial programming duringset-up of the trial period or for reprogramming, but does not requireinteraction by the patient during the trial period. Typically, controlor adjustment of stimulation by the patient would be performed by use ofthe patient remote. In some embodiments, the EPG is provided in ahibernation mode and communication can be initiated by actuation of abutton on the EPG to facilitate programming with the CP. In someembodiments, when the patient remote is used to turn stimulation off,the EPG returns to the hibernation state and only the CP can fully turnthe EPG to an off-state. In some embodiments, the EPG includes a singlebutton thereon configured as described in any of the embodiments herein.

FIGS. 8A-8B depict an exemplary neurostimulation lead configured for usea temporary lead for use in a trial, such as a PNE. FIGS. 9A-10Billustrate features of a proximal connector of the lead that facilitateimproved retention of the lead during the trial period. It isappreciated that any of the features described herein pertaining to thetemporary lead are applicable to any neurostimulation lead, includingfully implanted leads for use in a long-term or permanently implantedneurostimulation system.

As shown in FIG. 8A, the neurostimulation lead is defined by a coiledconductor 61 having an insulted coating along its length and a distalelectrode portion 62 defined by an exposed portion of the coiledconductor without the insulting coating. The distal end of the electrode62 includes an atraumatic tip 63 to avoid damage to tissues. In someembodiments, the atraumatic tip is formed by melting the distal tip ofthe exposed coiled conductor, for example by heating or welding, so asto form a ball-shaped tip. In some embodiments, the heat affected tipextends no more than 0.03″ from tip. The coiled lead can include one ormore markers 64 a, 64 b along an intermediate portion of the lead tofacilitate positioning and implantation of the lead at a targetedtissue. In this embodiment, the markers are defined by an open coilportion, the remainder of the lead being closed wound. In otherembodiments, the markers portions are stretched to form the open coilportion. In some embodiments, the lead is wound so as to form the opencoiled portions defining the markers and the closed wound portions. Thislatter approach is advantageous over stretching portions as it avoidsplastic deformation of the conductor and associated stresses on theconductor along the open coil portions. It is appreciated that themarkers can be defined by various other features, for example visiblemarkings, such as coating, applied onto the coiled conductor.

In one aspect, the dimensions of the lead are defined in accordance witha given application of the neurostimulation lead. The embodimentdepicted in FIG. 8A is configured for use as a PNE lead for sacral nervemodulation, the single electrode being inserted through a foramen needleinserted through a sacral foramen and positioned adjacent a sacral nerveroot. A sufficient length of the lead remains outside the patient forattachment to an external pulse generator, either directly or through anintermediate cable, for a nerve stimulation evaluation or trial. Forsuch an application, the overall length of the lead can be between 12″to 24″, typically about 16″. The length of the distal electrode can bewithin a range of 0.1″ to 1″, typically about 0.2″ to 0.6″, preferablyabout 0.4″. In some embodiments, the exposed surface area of the distalelectrode is within a range of 0.01 in² to 0.1 in², typically between0.02 in² and 0.05 in², preferably about 0.027 in². In some embodiments,the length and/or surface area of the lead corresponds to a lead of thepermanently implanted neurostimulation lead.

Typically, the outer diameter of the lead is about 0.025″ to facilitatepassage through a foramen needle. The lead includes two markers, visualmarker A (64A) and visual marker B (64B), positioned at two differentlocations corresponding to two differing lengths of respective foramenneedles. Visual marker A is positioned at a first distance (e.g. 4-5″)from a distal end of the lead for use with a first foramen needle of acorresponding length and visual marker B is positioned at a seconddistance (e.g. about 6-7″) from a distal end of the lead for use with asecond foramen needle of corresponding length. The differing lengthscorrespond to different locations at which the target region is locatedas suited for a particular patient or application. The open coiledmarkers can be between 0.1″ to 0.5″, or any suitable length. In theclosed wound portions, the pitch (taken as an average measurement over10 turns) is between 0.005 to 0.05″, typically about 0.010″. In the opencoil portions, the pitch is within a range of about 0.01 to 0.05″,typically about 0.03″. In this embodiment, each open coiled marker isabout 0.2″ in length. It is appreciated that such a lead could include asingle marker, two markers, or multiple markers corresponding todiffering locations as need for a given application.

As shown in FIG. 8B, the conductor can be comprised of a multi-filarconductor 60 a having an outer insulative coating 60 b. In thisembodiment, the conductor 60 a is a 7-strand wire of stainless steel(e.g., 316 SS) and the insulating coating thickness is between 0.0005″and 0.005″. The inner diameter can be within a range of 0.001 to 0.01″.The outer diameter can be within a range of 0.01 to 0.05″. It isappreciated that the above dimensions of the lead are suited for theparticular application of sacral neuromodulation described herein, andthat various other dimensions could be utilized as needed for a giventype of stimulation (e.g. spinal neuromodulation, deep brainstimulation).

In another aspect, a proximal end of the lead 60 is coupled to aproximal contact connector 66, the conductor being electrically coupledand fixedly attached to the proximal contact connector. In someembodiments, the proximal connector 66 is dimensioned for passagethrough the foramen needle, for example, in the application describedabove, the proximal connector has an outer diameter of about 0.025″. Anouter cover 65 a (e.g. shrink tubing) is applied over the interfacebetween the coiled conductor and the proximal connector 66. FIGS. 9A-10Bshow various detail views of the proximal contact connector 66 (shownbefore attachment to the coiled conductor).

As can be seen in FIGS. 9A-9C, the proximal contact connector 66includes a distal portion 66 a for electrically coupling with theconductor of the coiled conductor and a proximal portion 66 b forcoupling with an external pulse generator or intermediary cable andfacilitating handling of the lead. The distal portion 66 a includes adistal end 69, a retention flange 68 and a coupling portion 67 that isproximal of the retention flange. One or more coils at the proximal endof the coiled conductor are fixedly attached (e.g. by soldering or laserwelding) to coupling portion 67. The distal end 69 is sized to befittingly received within the inner diameter of the coiled lead. Theretention flange includes a distal facing ramped surface 68 a that istapered for facilitating introduction of the coiled conductor ontorecessed coupling portion 67. In this embodiment, the ramped surface 68a extends only partly about the circumference of the connector andincludes a notch 68 b that allows introduction of a proximal end of theconductor to be fed past the flange and onto the coupling portion, forexample, by screwing or gently pushing and rotating the conductor toadvance one or more coils onto the coupling portion 67. The retentionflange 68 further includes a proximal facing retention surface 68 c thatis substantially perpendicular to the longitudinal axis of the lead andconnector so as to retain the coiled conductor by engagement with a coilof the coiled conductor on the coupling portion.

Engagement of one or more coils of the coiled conductor against theproximal facing retention surface resists the load from tension on thecoiled lead and removes the load and stress concentration from the weldjoint of the conductor along the coil portion, thereby protecting theweld joint. In this embodiment, the retention surface is configured towithstand a minimum tensile force when the coiled conductor is pulled inthe distal direction. In this embodiment, the retention surface of theretention flange 68 is perpendicular to the longitudinal axis of theconnector 66.

The proximal portion 66 b of the connector extends a sufficient lengthto facilitate connection of the proximal contact connector to a pulsegenerator or intermediary cable. The proximal portion has a length, l,between 0.1″ and 0.5″, typically about 0.25″ and can include an indentedfeature, 65 b, to be used as a visual indicator for alignment of thecover (e.g. shrink tube) formed of any suitable material (e.g., polymer,PET). The indented portion can be spaced a distance 1 ₁ away from theproximal end of the connector, typically between 0.1 to 0.2″. Theproximal end 66 c includes an opening through which a style can beinserted through the proximal contact connector 66 and through the leadto the distal end to stiffen the lead and facilitate insertion of thelead through the foramen needle. After placement of the distal electrodeat the target electrode, the foramen needle can be removed and thestylet withdrawn. In this embodiment, the proximal end of the contactconnector 66 is tapered at angle a1, which can be between 30-60 degrees,typically about 40 degrees. The outside diameter of the proximal contactconnector is substantially the same as that of the lead to facilitatepassage through a foramen needle. In this embodiment, the outsidediameter is about 0.023″.

FIGS. 10A-10B illustrate further details of the distal portion 66 a ofthe proximal contact connector 66. As shown, the retention surface has awidth of 0.005″ extending circumferentially about at least part of thecoupling portion. In some embodiments, the retention surface issubstantially perpendicular (90 degree+/−10 degrees). It is appreciatedthat the stop feature could be slightly angled and still withstand adesired minimal tensile force. In this embodiment, the retention featureis configured to withstand a minimum tensile force, for example at least5 N, preferably at least 10-12 N. It is appreciated that this minimumtensile force can differ according to the mechanical properties of theconductor/lead configuration, as well as the region in which the lead isimplanted. The distal facing ramp surface 68 a can be distally taperedat an angle, a2, from the longitudinal axis. In some embodiments, theangle a2 is between 30 to 60 degrees, in the embodiment shown, thisfeature is about 45 degrees. The ramp surface can extend a suitabledistance, for example, between 0.002″ and 0.01″. The notch 68 b canextend along an angled, a3, about the circumference, for example between90 to 180 degrees. In this embodiment, angle a3 is about 140 degreesabout the circumference. The recessed coupling portion 67 extends asufficient distance for one or more coils to be positioned along theportion and electrically coupled and fixedly attached thereto, such asby bonding, soldering or laser welding. In some embodiments, thecoupling portion extends between 0.01 to 0.05″. In this embodiment, thecoupling portion 67 extends about 0.02″. While the above dimensionsprovide retention to withstand a minimum desired tensile force for theconductor coil configuration described above, it is appreciated thatthese dimensions can be modified as needed to provide a differentdesired retention force as appropriate for a given conductor or leadconfiguration or application.

In another aspect, a trial system can utilize a tined neurostimulationlead, similar or identical to the design of a permanently implantedtined lead, that is electrically coupled to an external pulse generatorby a lead extension cable. Such tined neurostimulation leads typicallyinclude multiple electrodes and often utilize proximal connectors thatmimic the connector receptacle of an IPG. Such connector receptacles arerelatively larger than the proximal contact connector of the PNE leaddescribed above. Such trial systems can be utilized for weeks or monthsto assess the efficacy of neurostimulation programs applied by animplanted multi-electrode neurostimulation lead. As describe above inthe trial system of FIG. 4, the proximal connector of the lead isimplanted within the body through a first incision area (typically at alocation at which the implanted pulse generator may later be implanted)and coupled to the lead extension cable which is tunneled to exit thebody at a second incision for electrically coupling to the externalpulse generator. This approach avoids potential infection of the firstincision area since the incision area through which the cable extends ina partially implanted system has a higher risk of infection. Themovement of the extension cable during the trial period along where itexits the body can introduce contaminants or bacteria leading to aninfection. Another challenge associated with the lead extension cable isregression of the distal connector through the second incision duringremoval of the lead extension cable and conversion of the system to afully implanted system. To avoid these challenges associated with use oflead extension cables, the extension cable can include a lead regressionstopper adapted to engage an outer surface of the skin (or a bandage orgauze placed thereon) so as to prevent regression of the lead extensioninto the patient's body during the trial period or during removal of thelead extension during conversion to a permanently implanted system. Thestopper is dimensioned with a distal facing surface to engage an outerskin of the patient (or associated gauze), yet still sufficiently smallto allow passage of the entire stopper through a cannula or deliverysheath tunneled from the first incision and through the second incision.

FIG. 11 shows an example lead extension cable 70 having a distalconnector 71 for coupling to the implanted tined lead, a proximalconnector 73 adapted for coupling with the EPG (or an intermediateconnector cable/adapter) and a lead extension cable 72 electricallycoupling the proximal and distal connectors. The distal connector 71includes contacts D1, D2, D2, D3 of a canted coil spring design (e.g.Bal-seal contacts) that mimics the connector receptacle of an IPG thatare electrically coupled to four contacts P0, P1, P2, P3 of the proximalconnector 73, as shown in FIG. 12B, which correspond to the fourconductors of the lead extension and four-electrode tinedneurostimulation lead. The distal connector 71 remains implanted withinthe patient's body at the first incision during the trial period, whilethe remainder of the lead extension cable is passed through an accessroute tunneled from the first incision and exits the body through asecond incision. To facilitate passage through the tunneled region, theproximal connector 73 and regression stopper 74 have a reduced deliveryprofile that corresponds to an inside diameter of the tunneling tool,for example, 0.4″ or less, or typically less than 0.2″ The regressionstopper 74 includes a distal facing surface 74 a that engages against anouter skin of the patient (or associated bandaging or gauze) when thelead extension is pulled inward toward the body, such as by flexing ofthe implanted lead or during the implantation or removal procedure. Forthe application described herein, the overall length, L1 of theextension cable is relatively long, for example, 30-40 inches. Thelength, L2, between the distal connector 71 and the regression stopper74 is about 10-20″, typically about 14 inches, and the length, L3, ofthe proximal connector is about 0.5-1″. Additional views of the leadextension 70 and internal connector components are shown in FIG. 13A andthe associated cross-sectional view in FIG. 13B (the regression stopperis not shown).

As shown, the regression stopper 74 is substantially cylindrical inshape, however, it is appreciated that various other shapes and designscould be utilized in accordance with the concepts described above. Insome embodiments, the regression stopper 74 can include a feature forcoupling to a removable stopper feature, for example, a stoppercomponent having a further enlarged diameter. The regression stopper canbe formed of a polymer, metal, or any suitable material. Typically, theregression stopper is relatively rigid, however, the stopper can besemi-rigid or malleable for patient comfort.

FIGS. 14A-14B show an example trial system 100 utilizing such a leadconnector 22 having a regression stopper 74.

FIG. 14B depicts a lead extension 22, which includes a proximal leadconnector 24 similar or identical to that on the implantableneurostimulation lead 20 and an implantable lead connector receptacle21, which can be connected to a proximal lead connector 24 of a fullyimplanted neurostimulation lead 20 and a regression stopper 74 asdescribed above. The proximal connector 24 is configured for attachmentto the EPG 40 via connector receptacle 42.

FIG. 15 illustrates a schematic of a trial system 100, in accordancewith aspect of the invention, and a permanent system 200 to furtherdemonstrate the applicable uses of any of the neurostimulation leadsdescribed herein. As can be seen, each of the trial and permanent systemare compatible for use with a wireless clinician programmer and apatient remote. The communication unit by which EPG wirelesslycommunicates with the clinician programmer and patient remote canutilize MedRadio or Bluetooth capability, which can provide acommunication range of about two meters. The clinician programmer can beused in lead placement, programming and stimulation control in each ofthe trial and permanent systems. In addition, each allows the patient tocontrol stimulation or monitor battery status with the patient remote.This configuration is advantageous as it allows for an almost seamlesstransition between the trial system and the permanent system. From thepatient's viewpoint, the systems will operate in the same manner and becontrolled in the same manner, such that the patient's subjectiveexperience in using the trial system more closely matches what would beexperienced in using the permanently implanted system. Thus, thisconfiguration reduces any uncertainties the patient may have as to howthe system will operate and be controlled such that the patient will bemore likely to convert a trial system to a permanent system.

FIG. 16 depicts a method of assembling a neurostimulation lead. Such amethod can pertain to include assembly of trial leads, such as PNEleads, as well as leads for permanently implanted applications. Suchmethods can include: feeding at least one coiled conductor over a distalretention flange of a proximal contact connector so as to position oneor more coils of the at least one coiled conductor along a reducedprofile coupling portion of the proximal contact connector proximal ofthe distal retention flange and electrically coupling and fixedlyattaching the coiled conductor to the coupling portion by soldering orwelding. Such methods further include engaging a proximal facing surfaceof the distal retention flange with a portion of the one or more coilsdisposed proximal of the retention flange so as to withstand tensileforces applied by tension in the lead, thereby maintaining the integrityof the electrical connection between the coiled conductor and theproximal contact connector. In some embodiments, an insulative polymercover such as shrink tube is advanced over the interface of the coiledconductor and the proximal contact connector for protection.

FIG. 17 depicts a method of utilizing a lead extension. Such methods caninclude: implanting a neurostimulation lead in a body of a patient suchthat a proximal end of the lead is disposed at a first incision area;tunneling from the first incision area to a second incision; connectinga distal connector of the lead extension at the first incision area andimplanting the distal connector at the first incision area, the distalconnector being electrically coupled with a proximal connector of thelead extension via an extension cable including a regression stopper;and passing a proximal connector and the regression stopper through atool or cannula tunneled from the first incision and through the secondincision outside the patient's body. The tool or cannula are thenremoved. Engaging, with the regression stopper, an outer skin of thepatient or a pad or gauze disposed thereon inhibit regression of thelead into the patient during a trial period or during explant of thelead extension. This prevents infection of the second incision site andfacilitates removal of the lead extension after the trial.

In regard to trial leads generally, for example a PNE lead, it isdesirable for such leads to be configured to fit within a deliveryneedle or cannula, such as a 20 gauge needle with an ID of 0.025″.Typically, such leads include at least one conductor and one distalelectrode for monopolar stimulation. In some embodiments, trial leadscan include multiple leads to allow for mono-polar stimulation atdiffering points during the trial, or to allow for bi-polar stimulationor sequential stimulation between differing electrodes. In someembodiments, trial leads include tissue retention features that minimizeacute migration of the lead during the trial period.

FIG. 18-23C depict various other features of neurostimulation leads. Itis appreciated that such features can pertain to any type ofneurostimulation lead, for example the trials leads, such as a PNE lead,or to permanently implanted leads, as well as any type ofneurostimulation application.

FIG. 18 depicts a coating of a neurostimulation lead 20 having barbs 75.Such barbs 75 can be configured uni-directionally to inhibit migrationof the lead in one direction, or bi-laterally so as to inhibit leadmigration in either direction. The barbs can be cut into the insulatingcoating of the conductor. Alternatively, the conductor could passthrough a lead body that includes barbed retention features.

FIGS. 19A-19C illustrate a coiled conductor lead 76 defined by amulti-conductor ribbon 78. As shown in the cross-section of FIG. 19C,the multi-conductor ribbon 78 includes multiple conductors 77, eachhaving an insulated coating and fixed in a line along the ribbon. Thelead body is defined by the multi-conductor ribbon and can be entirelyclosed wound, open coiled, or have combinations of portions that areclosed wound and open coiled. The distal portions of each conductor canbe exposed so as to form a distal electrode, the differing conductorsbeing exposed along differing locations along the lead so as to providea multi-electrode lead.

In another aspect, a multi-electrode neurostimulation lead can bedefined by a multiple conductors wound along a spiral or helical leadbody. In some embodiments, such leads can includes a lead body definedby a helix of conductors attached on an outside of a lumen tubing. Thehelical twists along the length of the lead body provide texturalsurfaces that provide for improve tissue retention. It is appreciatedthat any of the other features described herein (e.g. barbs) can also beused in combination with these features. FIGS. 20A-20B illustratecross-sectional view of two examples of such neurostimulation leads.FIG. 20A illustrates four conductors 78 wound about a central core orcentral lumen 79, the conductors being attached to an outer surface ofthe lumen tubing 79 a. FIG. 20A illustrates eight insulated conductors78 wound about a central lumen 79, the conductors being attached to anouter surface of the lumen tubing 79 a. An additional outer coating 80′can be applied along the outside of the conductors.

In another aspect, anchoring features for use with implantableneurostimulation leads are provided. Such features can be applied totrial leads, such as PNE leads, so as to maintain a position of the leadand improve accuracy of the trial assessment as well as permanentlyimplanted leads. In some embodiments, the neurostimulation lead includesa retractable anchor, a bioabsorbable anchor, and/or a bioabsorbableanchor with a radiopaque marker.

FIGS. 21A-21B show a neurostimulation lead 90 defined by a coiledconductor 91 that includes a distal anchor 92 that is retractable into acentral lumen by retraction of an elongate member 93, such as pullwireor tether, coupled to the anchor. FIGS. 21A and 21B show the lead 90before and after retraction of the anchor 92.

FIG. 22 shows a neurostimulation lead 90′ defined by a coiled conductor91 and having a distal anchor 94 that is made of a bioabsorbable polymerwhich dissolves within the time period of the implant so as to allow foreasy removal of the lead during explant. Optionally, the bioabsorbablelead contains a nonabsorbable radiopaque marker 94 a, which is leftbehind to be used as a location marker for permanent implantation. Themarker can be made of gold or platinum/iridium, or any suitablematerial.

In one aspect, the coiled lead includes an open pitch coil design or oneor more portions having an open pitch coil design along portions of thelead that are implanted. The open coiled markers noted above in regardto the markers remain outside the body. By including such open coilportions along the implantable length, the gaps between coil and/ortexture of the open coils provide more resistance to migration orregression of the lead. This feature can be utilized in any type ofneurostimulation lead.

In another aspect, anchoring features can include a helical tined anchorattached to the lead. Such a helical tined anchor can be attached overan outside of the lead along the lead body, along the electrode oradjacent thereto. In some embodiments, the helical anchor can beattached by placement within an open pitch coiled region of the lead. Inother embodiments, the helical tined anchor can be attached to a distalend of the lead and can also function as a lead stop for the stylet.

FIG. 23A shows a neurostimulation lead 110 defined by a coiled conductor91 and having a helical tined anchor 95 attached on the outside of thelead body along the electrode portion. FIG. 23B shows a neurostimulationlead 120 having helical tined anchor 96 intertwined within an openpitched region of the lead body. FIG. 23C shows a neurostimulation lead130 having a distal helical tined anchor 96 attached to a distal end ofthe lead and that further includes a distal atraumatic tip 97 that actsas an end stop for the stylet during implantation. In any suchembodiments, the helical pitch of the helical tined anchor can bedefined to match the pitch within the region of the lead body to whichit is attached. The anchor can be formed of any suitable material (e.g.polymer, metal, etc.). In some embodiments, the helical anchor is formedof Nitinol tubing cut into a helical configuration. The protruding tinescan be heat set into the expanded position. The Nitinol helical base canbe heat set to a smaller inner diameter than the lead body to provide aninterference fit, which can then be twisted to open and then loaded ontothe lead body. Upon release, the helical base automatically tightensonto the lead body providing a secure attachment to the lead. Whilethese features are described in regard to a single electrode coiledconductor lead, typically utilized as a trial lead, it is appreciatedthat any of these features could be utilized in a various other types ofleads, such as multi-electrode leads or permanently implanted leads, orvarious other applications.

In the foregoing specification, the invention is described withreference to specific embodiments thereof, but those skilled in the artwill recognize that the invention is not limited thereto. Variousfeatures and aspects of the above-described invention can be usedindividually or jointly. Further, the invention can be utilized in anynumber of environments and applications beyond those described hereinwithout departing from the broader spirit and scope of thespecification. The specification and drawings are, accordingly, to beregarded as illustrative rather than restrictive. It will be recognizedthat the terms “comprising,” “including,” and “having,” as used herein,are specifically intended to be read as open-ended terms of art.

What is claimed is:
 1. A trial neurostimulation system to perform apercutaneous nerve evaluation for sacral nerve stimulation therapy, thesystem comprising: a temporary evaluation lead for a nerve evaluation ofstimulation of a sacral nerve, the evaluation lead comprising: a singledistal electrode, a proximal connector comprising a single proximalcontact, and a single conductor electrically connecting the singledistal electrode to the single proximal contact, wherein the singleconductor is a multi-stranded wire, wherein the single conductor isexposed to surrounding tissue in which the lead is implanted; whereinthe single conductor is closed wound coiled along a majority of thelength of the evaluation lead and includes at least a portion that isstretchable to an open coil design between the distal electrode and theproximal contact, the open coil design comprising gaps between adjacentcoils, so as to provide resistance to migration or regression of thelead; and an external pulse generator configured for sacral nervestimulation, the external pulse generator comprising: a lead connectorthrough which the external pulse generator delivers stimulation pulsesto the evaluation lead electrically coupled thereto; a pulse generatorand associated circuitry that effect control of stimulation generated bythe external pulse generator; a battery power source for powering theexternal pulse generator during an evaluation period; and acommunication unit by which the external pulse generator wirelesslycommunicates directly with each of a clinician programmer device and apatient remote, wherein the external pulse generator is configured tocommunicate with the clinician programmer device to effect programmingof the external pulse generator with one or more stimulation programs,and is configured to communicate with the patient remote to adjuststimulation intensity of the one or more stimulation programs during theevaluation period.
 2. The trial neurostimulation system of claim 1,wherein the portion having the open coil design extends along at leastthe implantable length of the evaluation lead.
 3. The trialneurostimulation system of claim 1, wherein the portion having the opencoil design comprises substantially the entire coiled conductor betweenthe single proximal contact and the distal electrode.
 4. The trialneurostimulation system of claim 1, wherein the closed wound coiledconductor is configured to be stretched or elongated along alongitudinal axis of the lead.
 5. The trial neurostimulation system ofclaim 1, wherein the conductor is configured such that the gaps formbetween adjacent coils increase when the lead is stretched or axiallyelongated.
 6. The trial neurostimulation system of claim 1, wherein thesingle proximal connector is a single connector pin.
 7. The trialneurostimulation system of claim 6 wherein the connector pin isconfigured for electrically connecting to a distal connector receptacleof an intermediate cable extending between the proximal connector of theevaluation lead and the lead connector of the external pulse generator.8. The trial neurostimulation system of claim 1, further comprising: anintermediate cable extending between the proximal connector of theevaluation lead and the lead connector of the external pulse generator.9. The trial neurostimulation system of claim 8, wherein the evaluationlead is electrically coupled with the external pulse generator throughthe intermediate cable without any intervening connections or cables.10. The trial neurostimulation system of claim 1, wherein the singleconductor of the evaluation lead is coiled about a central lumen of theevaluation lead to allow passage of a stylet therein to stiffen theevaluation lead during implantation.
 11. The trial neurostimulationsystem of claim 1, wherein the coiled conductor has an insulatingcoating along a majority of a length of the evaluation lead and thedistal electrode portion is defined by an exposed portion of the coiledconductor without the insulating coating.
 12. The trial neurostimulationsystem of claim 1, wherein the evaluation lead further includes twovisual markers disposed along an intermediate portion thereof tofacilitate positioning and implantation of the lead at the sacral nerve.13. The trial neurostimulation system of claim 12, wherein the twomarkers are disposed at locations corresponding to lengths of twodiffering sizes of foramen needles.
 14. The trial neurostimulationsystem of claim 12, wherein the two markers comprise visible coatingsapplied to the coiled conductor.
 15. The trial neurostimulation systemof claim 1, wherein the evaluation lead is dimensioned for passagethrough a foramen needle to facilitate delivery through the foramenneedle and removal of the foramen needle over the evaluation lead. 16.The trial neurostimulation system of claim 1, further comprising: aforamen needle for performing nerve localization, the foramen needlehaving an inner lumen; wherein an outside diameter of the coiledconductor and an outside diameter of the proximal connector are eachdimensioned for passage through the foramen needle to facilitatedelivery through the foramen needle and removal of the foramen needleover the evaluation lead.
 17. The trial neurostimulation system of claim1, wherein an outside diameter of the temporary evaluation lead isbetween 0.01 and 0.05 inches.
 18. The trial neurostimulation system ofclaim 1, wherein a total length of the temporary evaluation lead isbetween 12 and 24 inches.
 19. The trial neurostimulation system of claim1, wherein a length of the distal electrode is between 0.2 and 0.6inches and the surface area is between 0.02 and 0.05 in².
 20. The trialneurostimulation system of claim 1, wherein the evaluation lead iswithout any dedicated anchor attached to an implanted portion of theevaluation lead and without any distal penetrating anchor.
 21. A trialneurostimulation system to perform a percutaneous nerve evaluation forsacral nerve stimulation therapy, the system comprising: a temporaryevaluation lead for a nerve evaluation of a sacral nerve, the evaluationlead comprising: a single distal electrode, a proximal connectorcomprising a single proximal contact, and a single conductorelectrically connecting the single distal electrode to the singleproximal contact, wherein the single conductor is a multi-stranded wire,wherein the single coiled conductor has an insulating coating along amajority of a length of the evaluation lead and the distal electrodeportion is defined by an exposed portion of the coiled conductor withoutthe insulating coating, wherein the single conductor is exposed tosurrounding tissue in which the lead is implanted; wherein the singleconductor is closed wound coiled along a length of the evaluation leadand includes at least a portion that is axially stretchable, such thatgaps between adjacent coils form when the lead is stretched or axiallyelongated, so as to provide resistance to migration or regression of thelead; and an external pulse generator configured for sacral nervestimulation, the external pulse generator comprising: a lead connectorthrough which the external pulse generator delivers stimulation pulsesto the evaluation lead electrically coupled thereto; a pulse generatorand associated circuitry that effect control of stimulation generated bythe external pulse generator; a battery power source for powering theexternal pulse generator during an evaluation period; and acommunication unit by which the external pulse generator wirelesslycommunicates directly with each of a clinician programmer device and apatient remote, wherein the external pulse generator is configured tocommunicate with the clinician programmer device to effect programmingof the external pulse generator with one or more stimulation programs,and is configured to communicate with the patient remote to adjuststimulation intensity of the one or more stimulation programs during theevaluation period.
 22. The trial neurostimulation system of claim 21,wherein the evaluation lead is dimensioned for passage through a foramenneedle to facilitate delivery through the foramen needle and removal ofthe foramen needle over the evaluation lead.
 23. The trialneurostimulation system of claim 21, wherein an outside diameter of thetemporary evaluation lead is between 0.01 and 0.05 inches and a totallength of the temporary evaluation lead is between 12 and 24 inches. 24.The trial neurostimulation system of claim 21, wherein a length of thedistal electrode is between 0.2 and 0.6 inches and the surface area isbetween 0.02 and 0.05 in².
 25. The trial neurostimulation system ofclaim 21, wherein the evaluation lead is without any dedicated anchorattached to an implanted portion of the evaluation lead and without anydistal penetrating anchor.
 26. A trial neurostimulation system toperform a percutaneous nerve evaluation for sacral nerve stimulationtherapy, the system comprising: a temporary evaluation lead for a nerveevaluation of stimulation of a sacral nerve, the evaluation leadcomprising: a single distal electrode for delivering stimulation to thesacral nerve, a proximal connector comprising a single proximal contact,and a single conductor electrically connecting the single distalelectrode to the single proximal contact, wherein the single conductoris a multi-stranded wire, wherein the single coiled conductor has aninsulating coating along a majority of a length of the evaluation leadand the distal electrode portion is defined by an exposed portion of thecoiled conductor without the insulating coating, wherein the singleconductor is closed wound coiled along a length of the evaluation leadand includes at least a portion in which adjacent coils are notmechanically connected or embedded within an outer cover such that thegaps between adjacent coils form when the lead is stretched or axiallyelongated so as to provide resistance to migration or regression of thelead; and an external pulse generator configured for sacral nervestimulation, the external pulse generator comprising: a lead connectorthrough which the external pulse generator delivers stimulation pulsesto the evaluation lead electrically coupled thereto; a pulse generatorand associated circuitry that effect control of stimulation generated bythe external pulse generator; a battery power source for powering theexternal pulse generator during an evaluation period; and acommunication unit by which the external pulse generator wirelesslycommunicates directly with each of a clinician programmer device and apatient remote, wherein the external pulse generator is configured tocommunicate with the clinician programmer device to effect programmingof the external pulse generator with one or more stimulation programs,and is configured to communicate with the patient remote to adjuststimulation intensity of the one or more stimulation programs during theevaluation period.
 27. The trial neurostimulation system of claim 26,wherein the evaluation lead is dimensioned for passage through a foramenneedle to facilitate delivery through the foramen needle and removal ofthe foramen needle over the evaluation lead.
 28. The trialneurostimulation system of claim 26, wherein an outside diameter of thetemporary evaluation lead is between 0.01 and 0.05 inches and a totallength of the temporary evaluation lead is between 12 and 24 inches. 29.The trial neurostimulation system of claim 26, wherein a length of thedistal electrode is between 0.2 and 0.6 inches and the surface area isbetween 0.02 and 0.05 in².
 30. The trial neurostimulation system ofclaim 26, wherein the evaluation lead is without any dedicated anchorattached to an implanted portion of the evaluation lead and without anydistal penetrating anchor.